In general, while a golf ball is flying, the golf ball subjects to frictional resistance in its front side and shape resistance in its rear side. The frictional resistance is applied to the golf ball due to the friction between the golf ball and air, and the shape resistance is applied to the golf ball due to the swirling of air which occurs behind the golf ball while the golf ball is flying.
Among the above-mentioned resistances, the shape resistance functions as a main factor of deteriorating the characteristics in trajectory and flight distance of a golf ball; in order to reduce the shape resistance, a plurality of recesses, so called “dimples,” are formed on the circumferential surface of the golf ball.
The air flow flowing around a dimpled golf ball is relatively slow as compared with that flowing around a non-dimpled golf ball; as a result, a swirling or backward flow generation area is reduced in such a dimpled golf ball, which is formed behind the golf ball while the golf ball is flying, whereby the shape resistance, which occurs as the backward air flow draws the golf ball in a direction opposite to the flight direction of the golf ball, can be lowered.
A conventional golf ball 1 also has a plurality of dimples 5 (e.g., in total of about 450 dimples) on the circumferential surface thereof as shown in FIG. 1, so as to reduce the above-mentioned shape resistance.
However, the conventional dimpled golf ball has a wide contact area, which will come into contact with the club face of a golf club 2, the contact area being formed between the dimples; due to the arrangement of the dimples, impact pressure is not uniformly to the golf ball over the entire contact surface on the golf ball with the club face at the moment the club face impacts on the golf ball. As a result, the impact angle is varied each time the golf ball is hit by the golf club, whereby it is very difficult to accurately hit such a golf ball.
In addition, the above-mentioned conventional dimpled golf ball has a disadvantage in that it cannot fly so far, because when it is hit by a golf club, it subjects to not only a high frictional resistance, which occurs due to air running against the front side thereof, but also a relatively high shape resistance, which occurs behind it, while it is flying.